Gets service entry by port.
Standard C Library (libc.a)
#include <netdb.h> int getservbyport_r(Port, Proto, servent, serv_data) int Port; const char *Proto; struct servent *servent; struct servent_data *serv_data;
The getservbyport_r subroutine retrieves an entry from the /etc/services file using a port number as a search key. An application program can use the getservbyport_r subroutine to access a service, service aliases, the protocol for the service, and a protocol port number for the service.
The getservbyport_r subroutine searches the services file sequentially from the beginning of the file until it finds one of the following:
Upon locating a matching protocol and port number or upon locating a matching protocol where the Port parameter value equals 0, the getservbyport_r subroutine returns a pointer to a servent structure, which contains fields for a line of information in the /etc/services file. The netdb.h file defines the servent structure, the servert_data structure, and their fields.
The getservbyport routine overwrites static data returned on subsequent calls. The getservbyport_r routine does not.
Use the endservent_r subroutine to close the /etc/services file.
| Port | Specifies the port where a service resides. |
| Proto | Specifies a protocol for use with the service. |
| servent | Points to the servent structure. |
| serv_data | Points to the serv_data structure. |
The function returns a 0 if successful and a -1 if unsuccessful.
| /etc/services | Contains service names. |
endservent_r Subroutine, setservent_r Subroutine, getservent_r Subroutine, and getservbyname_r Subroutine.